System, method, and computer program for superposition coded multicast with a single modulation scheme

Abstract

A cross-layer design architecture is provided for logical superposition coded (SPC) modulation for last-hop wireless data, aiming to overcome the effects of multi-user channel diversity in wireless video multicast. The proposed approach generates a logical SPC modulated signal by mapping successively refined information bits onto layered modulation through dynamic energy allocation and phase keying assignment, which mimics the superposition process for multiple modulated signals in convention hardware-based SPC modulation. At the receiver end, the received logical SPC signal is decoded by implementing a software-based approach on common demodulators without going through the signal-interference cancellation (SIC) process that is necessary in the conventional approach. The approach presented provides comparable or even better overall system throughput than by using the conventional hardware and SIC-based SPC modulation under various scenarios of different histograms of user channel conditions and power allocations for base and enhancement layer information.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to wireless communication, and more specifically to techniques for enabling wireless data multicasting requiring minimal hardware modifications to a transmitter and requiring no hardware modifications to a receiver.BACKGROUND TO THE INVENTION[0002]Multicasting or sharing a transmitted signal with information among a group of receivers who are interested in the same content (e.g. data, video, audio, etc.) is generally an effective and scalable way to deliver bandwidth-intensive data in wireless or even wired infrastructure because duplicated deliveries of the same copy of data can be prevented.[0003]Unprecedented advancements in wireless broadband access technologies based on IEEE 802.16 (WiMAX) standards and scalable video coding technologies, such as H.264 / MPEG4 Advanced Video Coding (AVC), have made it possible for provisioning large-scale wireless video multicast / broadcast services, such as mobile Internet Protoc...

AI Technical Summary

Benefits of technology

[0013]The present invention provides a method for transmitting data to one or more receivers linked to a transmitter by a wireless channel, the method characterized by: (a) separating the data into one or more layers, each layer represented by one or more bits; (b) combining the bits of the layers into a bitstream, each possible bitstream combination being representable by a unique data point; (c) generating a modulated signal by modulating the bitstream with a first modulation scheme, the modulation scheme operable to modulate at least as many unique data points as there exist possible bitstream combinations; and (d) transmitting the modulated signal to the one or more receivers, each receiver operable to demodulate at least one of the layers using the first modulation scheme or one or more other modulation schemes, the other modulation schemes operable to demodulate a signal having fewer possible data points than is the first modulation scheme.

[0014]The present invention also provides a system for transmitting data to one or more receivers, the system characterized by a transmitter linked to the one or more receivers by a wireless channel, wherein: (a) the transmitter includes or is linked to a data separating means for separating the data into one or more layers, each layer represented by one or more bits; (b) the transmitter includes or is linked to a bitstream generating means for combining the bits of the layers into a bitstream, each possible bitstream combination being representable by a unique data point; and (c) the transmitter includes or is linked to a modulator for generating a modulated signal by modulating the bitstream with a first modulation scheme, the modulation scheme operable to modulate at least as many unique data points as there exist possible bitstream combinations; wherein the transmitter transmits the modulated signal to the one or more receivers, each receiver operable to demodulate at least one of the layers using the first modulation scheme or one or more other modulation schemes, the other modulation schemes operable to demodulate a signal having fewer possible data points than is the first modulation scheme.

[0015]The present invention further provides a computer program product comprising computer instructions which, when loaded on one or more computer processors linked to a transmitter operable to transmit data over a wireless channel, are operable to provide a means for transmitting data to one or more receivers linked to the wireless channel, characterized in that the computer program is operable to perform the steps of: (a) separating the data into one or more layers, each layer represented by one or more bits; (b) combining the bits of the layers into a bitstream, each possible bitstream combination being representable by a unique data point; (c) generating a modulated signal by modulating the bitstream with a first modulation scheme, the modulation scheme operable to modulate at least as many unique data points as there exist possible bitstream combinations; and (d) transmitting the modulated signal to the one or more receivers, each receiver operable to demodulate at least one of the layers using the first modulation scheme or one or more other modulation schemes, the other modulation schemes operable to demodulate a signal having fewer possible data points than is the first modulation scheme.

Problems solved by technology

However, due to multi-user channel diversity among subscribers in receiving the same wireless multicast signal, it has long been an issue how to select a proper transmission rate.

A straightforward yet dummy solution could be such that the most conservative transmission rate is adopted to seek to satisfy as many recipients as possible, at the expense of a reduced number of TV channels that can be jointly provisioned, which certainly leads to a poor economic scale.

Current 3G technologies and previous wireless systems failed to justify such an addition of dedicated hardware and software support mostly due to the fact that video multicasting service subscriptions, such as scheduled IPTV, have not reached maturity.

These requirements pose both a significant technical barrier and interoperability concerns in adopting and deploying this standard approach for scalable wireless video multicasting in broadband wireless access (BWA) networks.

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